BEIJING (AP) — Officials on Thursday raised the death toll from a clash this week in China's heavily Muslim far west to 20, with police having shot a higher number of assailants from the Uighur ethnic group than previously reported.

The Xinjiang province's state-run website said nine assailants charged and slashed a crowd of civilians during Tuesday's violence in the Xinjiang community of Yecheng, killing 13 and injuring many others. Police then fatally shot seven attackers and detained two others, the report said.

Earlier state media reports put the overall toll at 12, describing it as a terrorist attack and saying 10 civilians and two assailants were killed. However, an overseas Uighur group, the Germany-based World Uyghur Congress, said local Muslims were lashing out over government oppression and that most victims were armed Chinese security personnel.

U.S. government-backed broadcaster Radio Free Asia quoted a local government official who described the immediate aftermath of the attack, saying that people were screaming and trying to flee the scene, a pedestrian shopping street. The official, identified as the head of Yecheng county's land management department and named Abdukeyim, described the attackers as Uighurs and the victims as being from the country's Han Chinese majority.

Washington-based Radio Free Asia also cited local residents as saying that an influx of Chinese migrants into the area had bred resentment among Muslim Uighurs who felt disadvantaged in the competition for jobs.

The bloodshed late Tuesday came at a sensitive time, ahead of next week's opening of China's national legislature, when authorities tighten security nationwide to prevent anything that would mar the annual session.

The government has failed to win over Uighurs and other ethnic minorities through policies to boost economic growth and incomes as it increases police presence and controls religious practices to deter displays of separatism. China's ethnic Tibetan regions have also been unsettled in recent months by scattered demonstrations and clashes with authorities, as well as self-immolations in protest against the government's policies.